Sophia Antipolis: After the release of the first specification on smart contracts on 18 January, members from the ETSI PDL group published a White Paper entitled “An Introduction of Permissioned Distributed Ledger (PDL)”.

Distributed ledgers have consolidated as one of the most disruptive applications of information technology that have appeared in recent years. Their ability to store any kind of data as a consensus of replicated, shared, and synchronized digital records distributed across multiple sites, without depending on any central administrator, together with their properties regarding immutability (and therefore non-repudiation) and multi-party verifiability opens a wide range of applications.

According to access permissions, there are two types of distributed ledger systems: Permissioned Distributed Ledger (PDL) and permissionless distributed ledger. In PDL, governance and corresponding access control policies are agreed by the participant community, thus better preserving privacy and allowing for a more efficient consensus protocol to achieve higher transaction speed and better energy-efficiency, three of the main concerns related to unconstrained, permissionless systems.

PDL as a ledger technology may be applied in a number of technologies, able to work together in different ways to support user applications. To leverage PDL to other technologies, a PDL reference architecture is needed, and draft ETSI GS PDL-012 currently in preparation develops a layered PDL reference architecture, based on three layers. Based on this architecture, PDL-enabled base technologies and PDL operational aspects can be considered.

Th ETSI White Paper aims to:

• Present a brief introduction on blockchain and distributed technology
• Summarize PDL work items and technologies that have been developed and are currently under development by ETSI Industry Specification Group (ISG) PDL
• Describe selected use cases that PDL technologies can be applied to
• Discuss advanced distributed ledger technologies (DLT) with standardization potentials in future, such as redactable ledgers and payment channel networks

The conclusion of the White Paper outlines that smart contracts will play a critical role in PDL, and the integrity through the entire lifecycle of a smart contract needs to be guaranteed. PDL can be leveraged to support various scenarios (e.g., mobile networks, distributed data sharing and management, and artificial intelligence and machine learning) by providing immutable ledgers, distributed trust, and incentivization and autonomous operations based on smart contracts. In addition, advanced distributed ledger technologies such as redactable ledgers and payment channel networks are emerging to enhance the performance of PDL networks. Those advanced DLT technologies also bring some new issues for further study.

The White Paper can be downloaded from our website.